4 x 4 (Keypad that is!)
Yep, it's a 4 x 4 keypad. With a PSoC 4 you can make use of a 4 x 4 keypad without the need for creating any polling software.
With the inbuilt clocks and UDBs (Universal Digital Blocks) you can create a simple keypad scanner that presents a unique hexadecimal scan code for each key.
The scan code is a latched with an accompanying strobe signal to signify a key press to its consumer.
The schematic below includes additional NOT (aka inverter) gates to turn on the LEDs to represent '1' bits for the above video. These are normally excluded for normal use.
The hexadecimal scan code is made up of bits R_1, R_0, ED_0 and ED_1 in that order (MSB to LSB) for;
0-3 Top row of keys from left to right
4-7 2nd row of keys from left to right
8-B 3rd row of keys from left to right
C-F Bottom row of keys from left to right
Here is a picture of the Keypad row strobe generator output. Only one row is active at any time.
These are the ROW[3:0] signals. They are generated by Row address generator in combination with a LUT (Look Up Table).
